We're dividing 501668 by 90 
The aim is to understand the frequency of 90 in 501668.

On to step 1:
The number 90 fits into 5 0 times, leaving a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Bring next digit (0) of the dividend behind the 5 and repeat the process: 50 / 90

Step 2:
When dividing 50 by 90, we get 0 with a remainder of 50.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 50 and we're left with 50.
Include the next digit (1) from the dividend after 50, then repeat: 501 / 90

Advancing to step 3:
When dividing 501 by 90, we get 5 with a remainder of 51.
Put 5 as the next digit of the answer. 
Result so far: 5.0
Subtracting 450 from 501 leaves us with 51.
Append the next digit (6) from the dividend to 51 and continue with: 516 / 90

Let's proceed to step 4:
90 can be fit into 516 5 times, resulting in a remainder of 66.
Write down 5 as next digit of the result. 
Result so far: 55.0
The remainder is 66 after subtracting 450 from 516.
Include the next digit (6) from the dividend after 66, then repeat: 666 / 90

Going ahead to step 5:
If we divide 666 by 90, we get 7 and a remainder of 36.
Record the quotient 7 as the next digit in the result. 
Result so far: 557.0
Subtracting 630 from 666 leaves us with 36.
Include the next digit (8) from the dividend after 36, then repeat: 368 / 90

On to step 6:
When dividing 368 by 90, we get 4 with a remainder of 8.
Use 4 as the next digit of our solution. 
Result so far: 5574.0
If we subtract 360 from 368, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 7:
90 can be fit into 80 0 times, resulting in a remainder of 80.
Use 0 as the next digit of our solution. 
Result so far: 5574.0
Deduct 0 from 80 and we're left with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

On to step 8:
When dividing 800 by 90, we get 8 with a remainder of 80.
The next digit of our result is 8. 
Result so far: 5574.08
If we subtract 720 from 800, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Let's proceed to step 9:
800 divided by 90 is 8 with a remainder of 80.
Record the quotient 8 as the next digit in the result. 
Result so far: 5574.088
Deduct 720 from 800 and we're left with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

In conclusion, the division gives 5574.088 with a balance of 0.008.